Prep your pan and oven. Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease it.
Mix dry ingredients. In a large bowl, whisk almond flour, protein powder, baking powder, baking soda, salt, and cinnamon until no lumps remain. Breaking up clumps now makes a smoother batter.
Whisk wet ingredients. In a separate bowl, whisk eggs, yogurt, milk, maple syrup or honey, vanilla, and oil until smooth and creamy.
Combine gently. Pour the wet mixture into the dry ingredients.
Stir with a spatula just until combined. The batter should be thick but scoopable. If it seems pasty, add a splash more milk.
Fold in add-ins. Gently stir in any mix-ins like chocolate chips or berries.
If using frozen berries, fold them in straight from the freezer to prevent streaking.
Fill the cups. Divide batter evenly among the muffin cups, filling each about 3/4 full. A large cookie scoop works well here.
Bake. Place on the middle rack and bake for 18–22 minutes. Muffins are done when the tops spring back to a light touch and a toothpick comes out mostly clean with a few moist crumbs.
Cool. Let muffins cool in the pan for 5 minutes, then transfer to a rack.
This helps them set and prevents soggy bottoms.
Taste and adjust. Try one warm. If you want a sweeter batch next time, add 1–2 tablespoons more maple syrup or a handful of mini chips.